Recording and control system and apparatus therefor



Dec; 26, 1939. ;r. R, HARRISON ,30

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Dec, 26, 1939. -'r. R. HARRISON 0 RECORDING AND CONTROL SYSTEM AND APPARATUS THEREFOR v 2 Sheets- Sheet 2 Original Filed Nov. 1, 1926 tion is to provide a novel galvano'meter'control' Reissued Dec. 26, 1939 j UNITED STATES PATENT OFFICE.

RECORDING AND CONTROL SYSTEM AND v APPARATUS THEREFOR Thomas R. Harrison, Wyncote, Pa., assignor to The Brown Instrument Company, Philadelphia, Pa., a corporation oi Pennsylvania Original No. 1,827,520, dated October 13, 1931', Serial No. 145,583, November 1, 1926. Applicatlon fol-reissue April 21 1939, Serial No. 269,293

' 14 Claims.

The present invention relates to improvements in automatic recording and control systems and apparatus therefor. j

More particularly the invention relates to sys tems and apparatus for controlling recorders,

switches, motors, valves, rheostats, and like devices in response to mechanical, chemical, electrical or other physical changes of conditions in order to make a record of the changeaor' to main,- tain predetermined physical conditions at a controlled point or points, or both. The invention in especially useful in temperature recording and pyrometric control systems where it is desired to record the conditions of temperatures at one or more remote points, for example in furnaces or kilns, and to regulate or control, either manually or automatically, physical conditions at the controlled points;

Various recording and control systems and apparatus have heretofore been proposed for operations of the character mentioned, but the prior systems have been more or less inaccurate in operation, complicated instructure, lacking in durability, and easily disarranged. One well known type of prior system is provided with a control galvanometer operated by currents produced by varatlons in conditions at the controlled point or points. Periodically operating mechanical means have been provided, that push a control galvanometer pointer out of its normal plane of movement to actuate a control member. The movement required for dislocation of the pointer from' its normal plane of movement and to actuate the control member introduces undue strains in the galvanometer and sufliciently heavy constructions must be utilized to withstand such strains. I As a result the galvanometer cannot be made sufllciently sensitive in practical operation of such systems to efiect sumciently accurate actuation of the mechanism. Furthermore, during the period of actuation of the control member the galvanometer pointer is held against movement so that for a' substantial period the galvanometer is prevented from assuming'a new position in accordance with changes in physical conditions. Thus an adjustment must be made in a series of steps which is an excessively slow process 101 many practical applications. A primary object of the present inven-.

mechan sm in which the use. of a very sensitive galvanometer is permitted thus avoiding appreciable errors due to the necessary mechanical clearance which must be allowed in mechanisms.

This is accomplished by eliminating the contacting mechanisms heretofore used and effecting the (Cl. 236-69) a v controls by utilization of means responsive to radiant energy to effect the control operations, avoiding mechanical strains from the galvanometer, thus permitting the use of more sensitive control springs and'replacing the galvanometer pointer by a mirror having much lower moment of inertia thus increasing the speed of motion of the galvanometer coil.

A further disadvantage of prior contacting galvanometer recording and control instruments oi! the type mentioned is that 'due to periodic or cyclic operation, a substantial portion of each cycle must be utilized for restoration of the parts and the adjustments are made intermittently while small adjustments are inaccurately made and diflicult to produce. Another object of the present invention is to provide a control mechanism in which adjustments are made independently of periodic or cyclic mechanisms, and in which finer adjustments of the mechanism may be made, and made more rapidly and without interruption, and a.

A further object of the invention is to provide a light sensitive control mechanism for making corrections that are in a direction corresponding to the direction of deviation of the controlled condition from a predetermined condition, and are made at a variable ratedependent upon the extent of deviation of the controlled condition from the predetermined condition. so that for greater de--- viations from the predetermined condition, cor-- rections are more rapidly applied.

Further objects of the invention will appear in the following detailed disclosure of a preferred embodimentthereof, and are such as may-be attained by a utilization ot the various principles, combinations and sub-combinations as hereinafter 'set forth} and as are defined by the, terms of} the appended claims. As shown in the drawings,

Figure 1 is a more or less diagrammatic i1lustration of the preferred form of my invention.

Figure 2 is a more or less diagrammatic plan view of, the form of invention shown in Figurel.

Figure 3 is a, diagrammatic'illustratlon showing the essential control circuits of the preferred embodiment of my invention.

A control galvanometer of unusual construction provided with the galvanometer coil I held in normal position by springs IA and IB, is con the galvanometer coil I is a mirror 4 and extending from opposite sides of the galvanometer coil deflection of the coil. The stops '5 are employed as a matter of practical convenience and are-in no way inherently necessary to the operation of the device of this invention. They may be omitted. Stop members are adapted to engage the ends of stop projections 6 which are formed integrally on upstanding support 1 of the control table 8. As will be described in detail hereinafter the control table 8 is rotated thereby moving the stop projection 6 to vary the limits between which the galvanometer may deflect. Control table 8 is journaled for rotation on spindle 9. Spindle 9 is supported by journals l6 and l I, and rigidly secured thereto is the recorder ribbon driving pulley l2 around which metallic recorder ribbon l3 passes. through the boss I4 of the table 8, and has secured thereto and is driven by a worm wheel l5. Worm wheel l5 meshes with a drive worm I6 secured to and driven by a shaft I1.

l8. Secured to theouter end of the shaft I1 is a bevel gear l9 which meshes with and is driven by a bevel gear 20. Gear 26 is in turn secured to and driven by a shaft 2| whichis supported from the table 8 by means of the journals 22 and 23. Secured to and driving the shaft 2| is a friction disk 24 which normally contacts with the center of drive disk 25. Drive disk 25 is supported on the upper end of and driven by a shaft 26 which is suitably journaled at 21 and 26 and is driven by a worm wheel 29. Worm wheel 29 in turn is driven by a worm 30 which is driven by the continuously operating motor 3|.

Rigidly secured to and driving table 6 is a gear 32 which is journaled for rotation on spindle 3 which meshes with and is driven by a gear 33. Gear 33 in turn is secured to and driven by the armature shaft 34'of a reversible motor 35. Rever'sible motor 35 is controlled by means of a circuit in which the current flow is varied in response to the variations in resistance of a pair of selenium cells 36 and 31 supported on panel 36.

Panel 36 in turn is supported on and movable with the table 6 by means'of the post 39. Selenium cells 36 and 31 are positioned to intercept a beam of light that is reflected from the mirror 4.

As shown in Figure 3 a source of light" is provided from which a light beam 4| passes through the converging lense arrangement 42 and l is directed through a fixed screen 43 and focused on the center of. the mirror 4 carried by the galvanometer coil I Beam 4| is reflected by mirror 4, passing through the piano-convex cylindrical lense 44 which, condenses the beam in a vertical direction, an" directs it on the selenium cells, 36 and 31*. Selenium cells 36 and 31 are connected in a Wheatstone bridge circuit. A terminal of cells 36 and 31 respectively are 'connected by means of conductors 45" and 46 through adjustablebalancing resistances 41 and 43 to terminals of the batteries 46 and 56. Conductors 45 and 46 are connected together at junction- Spindle, 9 extends Shaft IT in turn is supported from table 8 by the journals the direction of reflection of the coil 54 from the are the stop members ,5 which limit the extent of normal or zero position shown. Contact 53 is connected bymeans of the conductor 62 through a source of electrical energy 63 to the common terminal of reversing motor 35, while contacts-60 and 6| are connected to the remaining terminals of reversing motor 35 by means of conductors 64 and 65.

In operation of the device, drive disk 25 is rotated continuously by the motor 3|. galvanometer coil I in normal or zero position beam 4| will rest equally on the selenium cells 36 and '31 balancing the bridge circuit and no current will flow in bridge connection of the Wheatstone bridge circuit comprisingthe galvanometer coil 54. Contact 59 will accordingly be out of engagement with contacts 63 and GI and no energy will be supplied to motor 35, friction disk 24 will be in engagement with the center of the disk 25 as shown in Figure 2, and no rotation will be impartedthereto.

When a deflection of galvanometer coill from normal occurs, mirror 4 will move with it, shift: ing the reflected light beam 4| so that the amount of light impinging upon the cells 36 and 31 will become unequal, varying the resistances thereof in well known manner. This will unbalance With the the Wheatstone bridge circuit, causing a current v conductors 62 and-64 to reversing motor-35, starting the motor intorotation. Rotation of motor 35, rotates gear 32 which in turn causes the table 8 to rotate about spindle 3 in such a direction that the table 8 together with the selenium cells 36 and 31 will follow the beam 4| until it again falls equally on the selenium cells 36 and 31 balancing the bridge circuit.- When the bridge circuit is balanced, coil 54 and arm 56 will be returned to normal position shown in Figure 3, interrupting the circuit between contacts 59 and 60. As the galvanometer coil 1 restores to normal position, the beam of light will again be deflected causing unbalancing in the resistance of the selenium cells in the Oppositedirection so that current will flowthrough the coil 54 in an opposite Grection causing contact to engage the contact L, This closes a vcircuit for motor 35 through conductor", source 63, and conductor 65, causing the rotation of motor 35 in a reverse direction rotating the table 3 towards its normal position shown'in Figure 2. If coil I deviates from its normal positionin an opposite direc-' tion, contacts 53 and ii "will be closed and the table 6 will be moved in the opposite direction until the light beam again rests equally on cells 3i and 31. In this way it will be seen that the table 8 will be shifted to bring the selenium cells 36 and 31 to a position where the light beam 4I will fall equally on the cells, and accordingly the position of the table I will follow the movement of the light beam and the deflections of the galvanometer I.

As the table 8 isshifted from its normal position, friction driving wheel 24 will be moved off the center of the driving disk 25. As the wheel 24 moves of the center of wheel disk 25-it will be driven at a speed and in a direction that will vary with the extent and direction of movement respectively from the center of the disk 25. R0- tation of disk 24 drives the bevel gear 20 which in turn drives pulley I2 and belt I3 through bevel gear I9, shaft II, worm gear I6; and worm wheel I5. It will accordingly be noted that the disk 24 and the parts driven thereby including the ribbon I3, will remainat rest so long as the parts are in normal position, but upon deviation from normal position these parts will be driven at a rate that will vary with the extent of deviation from the normal condition and in a direction that will vary. with the direction of deviation from the normal condition. It will be obvious to those skilled in the art that the ribbon l3 may be the pen or printing hammer carrying ribbon of a well known type of recorder mechanism.

As will be evident from a description of the.

construction of the particular embodiment of the invention herein disclosed, it may be used either in a manner corresponding to that of the operation of a millivoltmeter or in a manner corresponding to that of the operation of a potentiometer. If the motor II the disc 25, the disc 24, the driving connections between disc 24 and shaft 9 and the pulley wheel I2 be omitted, the device will then operate ,as a millivoltmeter. Such operation would be as follows:

A source casts a beam of light directed by the galvanometer I, upon the selenium cells or other device sensitive to radiant energy. Deflection of the galvanometer I causes a shifting of the light falling upon the selenium cells resulting in a flow of current through the relay associated with contacts 59, and BI, causing a circuit to be closed at said contacts to set reversible motor 35 into operation, which moves the table 8 and the selenium cells to follow the beam of light, the" movement continuing until the radiant ener y sensitive device occupies the same position re ative to thebeam of light as before: thus the table 8 and the parts associated'therewith form. in effect, a millivoltmeter pointer operated by auxiliary means to takes un'a position corresponding to the deflection of the galvanometer I through the action of .the light beam. The control contacts 66," 51 and 68 may be actuated'by such deflection of the table 8 to produce an anpropriate control effect. Thus the position of the table 8 and contacts associated therewith. correspond to the deflection of the galvanometer I.

Where it is desired to use this invention in the form of potentiometer, the pulley I2 and pulley band associated therewith, togetherwith their driving mechanismconsisting ofparts I5, I6. Il,

I9,'2I, 25, 26, 29, 30 and SI, are employed. With such parts or their equivalent included in the mechanism of the particular embodiment of the invention herein disclosed, the mode of operation is as follows:

- The deflections of the galvanometer I act through the light beam to cause movement of the table 8 and associated radiant energy device in-the manner described-in the'previous para- .original deflection of the galvanometer graph. The movement of the table 8 causes the disc 24 to be shifted relative to the disc 25 so that the disc 24 takes up rotation from the disc 25, the direction of rotation and rate of rotation of the disc 24 being determined by the extent and direction of the displacement of the disc 24 relative to the center of the disc 25, a greater deflection producing a greater rotation. The disc 24 drives the band I3, which carries a potentiometer slide wire contact and may or may not carry a pen carriage and/or indicator, and/or control contacts. The adjustment of the potentiometer slide wire by the movement of the band I3 changes the constant of the measuring circuit associated with the galvanometer; I, thereby tending to return the deflecting member of the galvanometer I to its normal position.

The resulting movement of the deflecting member of galvanometer I shifts the light beam and causes in a manner before described,.the radiant energy device and table 8 to .follow the light beam and return to a normal or neutral position of the instrumentf Where the I is of large extent, the movement of the disc 24 will correspondingly be large and accordingly the adjustment of the potentiometer slide wire and the return of the deflecting member of the galvanometer member I to neutral be correspondingly rapid. As the galvanometer deflecting member returns to neutral, the table 8 in following the beam of radiant energy moves the disc 24 toward the center of the disc 25 so that the rate of adjustment of the slide wire contact is changed at a rate graded according to the rate of approach of the instrument to neutral condition.

Inasmuch as the operation of the galvanometer I, of the radiant energy sensitive measuring system, and of the. drive for adjusting the table 8,

. continuously adjusted to such a position as to tend to maintain the deflecting member of the galvanometer I in neutral position.

When it is desired to operate a control circuit .with the mechanism, a control switching mechanism may obviously be actuated by the ribbon I3 such as shown in Patent bio-1,898,183, granted Feb. 21, 1933, on my'copending application may be utilized, in a manner obvious to those skilled in the art, or a simple control arrangement may as shown in Figure 3 to a potentiometer with slide wire operated by belt I3,"and to a thermoelectric device, such for example a-thermocouple,

u provided by securing to the'table 8 a contact 1 brush 66 which, depending upon the direction of the furnace control may be actuated by a switch-- to control. Ribbon l3 may actuate a recording pen to make a record of the temperature variations, and selective switching mechanism'to control the supply of heat energy to the furnace, or

ing mechanism controlled by the conductors 69, (I and H. When the pen carried by belt l3 shows the temperature-of the thermocouple, the parts assume the position shown in the drawings. when a deviation of the temperature occurs, the galvanometer I will be deflected in a direction and to, an extent depending upon the direction and extent of'deviation of the temperature. The deflection of the galvanometer I causes the movement of table 8 in a direction corresponding thereto asabove set forth, and will cause the driving oi ribbon l3 to shift the pen carried thereby and will at the same timemove the slide wire contact until the potentiometer is again balanced and the pen position shows the correct v temperature.

til)

Instead of driving the ribbon l3 by means of the drive disk 24 and friction disk 25, it will be obvious to those skilled in the art'that this mechanism may be eliminated and the ribbon l3 may be driven by an independent gear train from reversing motor 35, or by securing the table 8 rigidly to the spindle 9 so that pulley I! will be,

turned with the table 8 by the reversing motor.

It will be apparent to those skilled in the art that the mechanism disclosed is applicable to a wide range of uses, and the details thereof may be widely varied without departing from the spirit of my invention. For example, stops 6 and parts 31 and 38 may be stationary, and extension I of movable arm 8 may be attached to control springs IA and IE to vary the torque of these springs to maintain coil l and mirror in the same normal position necessary to direct radiant energy upon sensitive'elements 31.

While the particular embodiment of the invention has been described by way of illustration, it is not intended so to limit the invention; for example, thesource of radiant energy may be other than a source of light, and the radiant energy may be. other than the beam of light. Any form of electromagnetic radiation may be used. The means operating to direct the beam of radiant energy may be other than a mirror as speciflcally disclosed. In the case of light radiation,

the directing means may be any convenient form of optical system. .The means for detecting or responding to the beam of radiant energy may be other than selenium cells such for instance as thermocouples, bolometers, photoelectric cells,

etc., arranged in an operating circuit characteristic of the particular radiantenergy sensitive 1. In a self-balancing measuringsystem comprising a galvanorneter and rebalancing means, the combination of a, source of light projecting a beam of light, a member carried by said galvanometer for directing said beam, means for un-' balancing said system and thereby causing said galvanometer and member to deflect on a variation in the value of the quantity measured, light sensitive means responsive to said beam, and

. r 21,309 subjected to the furnace temperature'it is desired means operable bysaid light sensitive means and tending on the occurrence of said variation to maintain the latter in the path of said beam, and to actuate the first mentioned means to effect a rebalancing adjustment of said system.

2. In a self-balancing measuring system comprising a .galvanometer and rebalancing means,

.the combination of 'a source of light projecting operable by said light sensitive means tending to maintain said light sensitive means in the path of said beam, an adjustable recorder and means actuated by the second mentioned means to effect a-rebalancing adjustment of said system and a corresponding adjustment of said recorder.

3. In combination, a galvanometer, a source of light projecting a beam of light, a member carried by said galvanometer, for directing said beam, light sensitive means responsive-to said beam, and means operable by' said light sensitive means tending to maintain said light sensitive means in the path of said beam, together with control mechanism for said galvanometer actuated by said last mentioned means. 4

'4. In a self-balancing measuring system comprising a; galvanometer and rebalancing means, the combination of a source of light projecting a beam of light, a member carried by said galvanometer for directing saidbeam, means for un- 1balancing said system and thereby causing said light sensitive means in the path of said beam,

and to effect a rebalancing adjustment of said system wherebythe first mentioned adjustment is eliminated.

5. In combination, a source of directed radiant energy, a deflecting member adapted to deflect from a normal position on a change in a controlling condition and operating on such deflection to modify the path of the directed radiant energy, a member sensitive to said radiant energy, means for adjusting the position of the last mentioned member relative to said path in response to changesin the latter, and control mechanism variably operated in accordance with the direction and extent of deviation of said deflecting member from a normal position, and tendingto modify said controlling condition so as to return said deflecting memberto its normal position.

6. In a control system, a galvanometer, including a deflecting member, means for deflecting said member, means for positively limiting the extent of deflection of said deflecting member and means responsive tothe deflection of said deflecting member for shifting said limit of deflection I of said deflecting member and for simultaneously effecting a control action tending to effect a reverse deflection of said member,

'7. In acontrol system, a galvanometer including a deflecting member, means for normally balancing said galvanometer, radiant energy responsive means for ,unbalancing said galvanometer and operating its deflecting member on a departure from normal of a control quantity, means responsive to the operation of said deflecting mem- -ber tending to temporarily balance we galvaative tor eflecting a control action tending to permanently rebalance said galvanometer.

9. In a control system, means responsive to temperature variations from a predetermined temperature for varying the supply of fuel for maintaining said predetermined temperature, radiant energy responsive means for rendering the first mentioned means temporarily unresponsive to such variations while continuing to vary the supply oi. fuel for again obtaining said prede- V termined condition, and means again rendering the first mentioned means responsive to such variations and preventing it from eflecting iuriner change of fuel supply when the temperature has again attained the predetermined'value. 10. In a self-balancing measuring and control system, means operable to vary the supply 01 fuel to maintain a predetermined temperature, means responsive to temperature variations from a predetermined temperature unbalancing said system and operating the first mentioned means on each such variation, system rebalancing means, and radiant energy responsive means operating on each such variation to operate said rebalancing means, and to render the second mentioned means unresponsive to the extent of the existing variation irom said predetermined temperature, without interrupting the operation of the first mentioned means.

ii. In a control system, a galvanometer responsive to temperature variations, control apperatus operated under control of said galvanometer tor varying fuel supply to control said temperature and radiant energy responsive means simultaneously operative with the control apperatus tor rendering the control apparatus inoperative for further variations of said i'uelsupply.

12am combination, a course of light, a light deflecting member adjustable on a change in a controlling condition irom-a normal position into ,diflerent positions depending on the extent of said change and receiving light irom said source .gganddeflectingitinadirectionvarylngwiththe position oi said member, apparatus receiving 8 1 GM bysaidmemberandccmprisinga sensitive device which when said member is in its normal position is in a normal position relative to the path of the light coming to said apparatus to receive a definite portion 01' the light deflected by'said member, adjusting means actuated by said device to rapidly efiect a compen-- sating adjustment oi the position of said device relative to said path on a change in said relative position resulting from a change in the position or said membenand condition controlling means actuated on movement of said member out or its normal position to slowly return said member to said normal position.

13. In combination in a self-balancing measuring system, a source of light, a light deflecting member adjustable when said system becomes unbalanced, from a normal position into a diilerent position dependent on the extent of unbalance, and receiving light from said source and deflecting it in a direction varying with the posi tion of said member, apparatus receiving light deflected by said member and comprising a sensitive device which when said system is balanced is in a normal position relative to the path of the light coming to said'apparatus to receive a definite portion of the light deflected by said member, means actuated on a change in the position of said device relative to said path to effect a,

relatively rapid conpensating adjustment neutralizing more or less of said change and means actuated on said change to eflect a relatively slow rebalancing adjustment of said system returning said member and device to their said normal positions.

1'4. In a measuring and control system, the

each of said parts, and means responsive to a.

change in the 'value'ot said controlling condition tending to deflect said member into engagement with one or the other of said parts, and means operative on such deflection, to actuate said controlling means in the direction to reverse said change in the value c! the controlling condition, and to eflect an adjustment of said measuring means tending to move said deflecting member relative to said parts toward a position intermediate thereof. I 1 THOMAS R. HARRISON. 

